More than 50 farmworkers in California became sick from pesticide drift, Kern Golden Empire reported, one month after a controversial pesticide was deemed safe to use by the Trump administration.

On May 5, workers harvesting cabbage on a farm near Bakersfield were exposed to a “pesticide odor” from mandarin orchards in the west sprayed with Vulcan, an organophosphate-based chemical. The active ingredient in Vulcan is chlorpyrifos, a chemical linked to human health problems manufactured by Dow AgroSciences, a division of Dow Chemical. Chlorpyrifos was slated to be banned by the U.S. Environmental Protection Agency under the Obama administration.

Approximately 12 people with symptoms of vomiting and nausea were decontaminated, but 11 of those 12 refused any further treatment, according to an incident log on the Kern County Fire Department webpage. One person was taken to the hospital while more than half of the farmworkers left before medical personnel arrived on scene. The Kern County Fire Department, Kern County Environmental Health and Hazmat responded to the area for a mass decontamination.

“I’m not pointing fingers or saying it was done incorrectly. It was just an unfortunate thing the way it was drifted,” Efron Zavalza, Supervisor and Food Safety Specialist at Dan Andrews Farms where the incident occurred, told the publication. “The wind came and pushed everything east and you know we were caught in the path.”

Chlorpyrifos — a widely-used organophosphate insecticide in use for over 50 years — is used on a variety of crops like oranges, apples, cherries, grapes, and broccoli. It can cause neurotoxic symptoms in humans like nausea, dizziness, and confusion. When exposed to high dosages, humans can suffer from respiratory paralysis or death. A study by researchers at Columbia University found that exposure was linked to brain function and lower IQ among children. For years, environmental groups have pressured the EPA to look into the correlation between pesticide usage and problems that could affect workers on an organic and cellular level.

During the Obama administration, EPA scientists recommended taking chlorpyrifos off the market. Despite the scientific evidence, new EPA Administrator Scott Pruitt rejected the ban on chlorpyrifos on the grounds that the agency needs to “provide regulatory certainty” for the thousands of U.S. farms that rely on chlorpyrifos. Dow Chemical donated $1 million to fund Presdient Donald Trump’s inauguration ceremony. In a letter to the Trump administration sent in April, Dow Chemical asked the administration to “set aside” and ignore research showing that the pesticide could be harmful to endangered species.